The spot light

A spot light is defined by a position, a direction, an angle and an exponent. These values define a cone of light starting from the position toward the direction. The angle defines the size of the spotlight beam and the exponent defines the speed of the decay of the light with distance:

A red diffuse spotlight with white specular and a 0.8 radians wide cone. The exponent value is 2.

The hemispheric light

Hemispheric light represents a simple and easy way to simulate realistic ambient light. An hemispheric light is defined by a direction to the sky and by 3 colors: one for the diffuse (the sky color), one for the ground (the color when the pixel is not towards the sky) and one for the specular.